ALBERT

Description: Graphic displays that have proved useful in dealing with vector magnetograph data are summarized in three settings: real-time control, analysis, and final presentation. Among the topics discussed are: flexible, implicit data-scaling; geometrical transformations; methods of comparing fields (e.g., transverse vs. longitudinal; observed vs. computed; one time vs. another); displaying the magnitude and direction of the transverse field; minimizing the display time of serial graphics devices; graphic file structure; and graphic interaction with operators and observers.

Description: In NOAA Active Region 2372 (April 1980), 4 x 10 to the 20th power maxwell of magnetic flux concentrated within a 30" circular area disappeared overnight. Vector magnetograms show that all components of the magnetic field weakened together. If the field had weakened through diffusion or fluid flow, 80% of the original flux would still have been detected by the magnetograph within a suitably enlarged area. In fact there was at least a threefold decrease in detected flux. Evidently, magnetic field was removed from the photosphere. Since the disappearing flux was located in a region of low magnetic shear and low activity, it is unlikely that the field dissipated through reconnection. The most likely possibility is that flux submerged. Observations suggest that even in the growth phase of active regions, submergence is a strong process comparable in magnitude to emergence.

Description: In this paper a summary and synthesis are presented for results on the role of magnetic shear in the flare process that have been derived from the series of Flare Buildup Study Workshops in the Solar Maximum Analysis program. With emphasis on observations, the mechanisms that seem to produce the sheared magnetic configurations observed in flaring active regions are discussed. The spatial and temporal correlations of this shear with the onset of solar flares are determined from quantitative analyses of measurements of the vector magnetic field. The question of why some areas of sheared magnetic fields are the sites of flares and others are not is investigated observationally.

Description: Solar physics has been successful in characterizing the full vector magnetic field in the photosphere, where the ratio of gas pressure to magnetic pressure (Beta) is 〉1. However, at higher levels in the atmosphere, where Beta 〈〈1 and flares and CMEs are believed to be triggered, observations are difficult, severely limiting the understanding of these processes. In response to this situation, we are developing SUMI (the Solar Ultraviolet Magnetograph Investigation) a unique instrument designed to measure the circular and linear polarization of upper chromospheric Mg II lines (280 nm) and circular polarization of transition region C IV lines (155 nm). To date the telescope mirrors have been built, tested and coated with dielectric stacks designed to reflect only the wavelengths of interest. We have also developed a unique UV polarimeter and completed the design of a high-resolution spectrograph that uses dual toroidal varied- line-space (TVLS) gratings. Incorporating measurements of those components developed so far, the revised estimate of the system throughput exceeds our original estimate by more than an order of magnitude. A sounding rocket flight is anticipated in 2006. Our objectives and progress are detailed in this presentation.

Description: The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a soundingrocket payload that obtains imaged high-resolution spectra of individual solar features, providing information about the Sun's corona and upper transition region. Shortly after its successful initial flight last year, a complete end-to-end calibration was carried out to determine the instrument's absolute radiometric response over its Longwave bandpass of 300 - 370A. The measurements were done at the Rutherford-Appleton Laboratory (RAL) in England, using the same vacuum facility and EUV radiation source used in the pre-flight calibrations of both SOHO/CDS and Hinode/EIS, as well as in three post-flight calibrations of our SERTS sounding rocket payload, the precursor to EUNIS. The unique radiation source provided by the Physikalisch-Technische Bundesanstalt (PTB) had been calibrated to an absolute accuracy of 7% (l-sigma) at 12 wavelengths covering our bandpass directly against the Berlin electron storage ring BESSY, which is itself a primary radiometric source standard. Scans of the EUNIS aperture were made to determine the instrument's absolute spectral sensitivity to +- 25%, considering all sources of error, and demonstrate that EUNIS-06 was the most sensitive solar E W spectrometer yet flown. The results will be matched against prior calibrations which relied on combining measurements of individual optical components, and on comparisons with theoretically predicted 'insensitive' line ratios. Coordinated observations were made during the EUNIS-06 flight by SOHO/CDS and EIT that will allow re-calibrations of those instruments as well. In addition, future EUNIS flights will provide similar calibration updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI.